This study investigated racial/ethnic differences in meeting the aerobic component of the DHHS Physical Activity Guidelines among adults with and at risk for RKOA. Our results showed that despite the known benefits from physical activity, only 1 out of 50 African Americans and less than 1 out of 8 Whites met Guidelines when objectively assessed via accelerometer. After adjusting for social-demographic and health factors, African American rates for meeting Guidelines were less than one-third of their Whites counterparts; these differences remained significant in the RKOA subgroup and substantial but insignificant in adults at risk for RKOA.
The current 2008 Guidelines are less strict than earlier recommendations, by allowing the activity to be acquired over a week without daily specifications (≥ 150 minutes of MV activity/week) and can take into consideration persons who do a mix of both moderate and vigorous intensity activity. When Guidelines were applied to the general adult population surveyed by the 2007 Behavioral Risk Factor Surveillance System (BRFSS)33
and 2005–2006 National Health and Nutrition Examination Survey (NHANES)25
self-reported physical activity data, similar racial differences were found (OR range: 0.54–0.63). In contrast, accelerometer measured objective physical activity data of the NHANES sample did not show strong racial/ethnic differences in meeting the Guidelines (OR = 0.93).25
However, other NHANES findings indicate that racial/ethnic differences were age-specific.23
African Americans under age 60 compared to Whites on average spent more time in objectively measured moderate and vigorous physical activity, but among adults over age 60 this trend was reversed. Those NHANES results corroborate the current results documenting racial/ethnic differences in an older chronic disease cohort. These studies in the general population showed strong racial/ethnic disparities in meeting guidelines when based on self-reported physical activity data, but ambiguous results when physical activity was objectively measured.
Literature on racial/ethnic differences in meeting physical activity guidelines among adults with arthritis is limited. Self-reported physical activity data from the 200034
, and 2003 BRFSS36
were applied to the 2003 physical activity guidelines (≥ 30 minutes of moderate-intensity physical activity on 5+ days per week or ≥ 20 minutes of vigorous-intensity physical activity on 3+ days per week37
) in arthritis populations. All three studies showed African Americans were less likely than Whites to meet the 2003 guidelines (OR range: 0.49–0.74). To our knowledge no studies from arthritis populations used objective physical activity measurements to assess racial/ethnic differences in guideline attainment. Our study fills this gap by demonstrating large racial/ethnic differences in meeting the current Guidelines using accelerometer-monitored physical activity in adults with RKOA.
To guide public health and policy intervention, we examined modifiable health factors that may mediate racial/ethnic differences. Obese/overweight status and greater knee pain partially attenuated racial/ethnic differences for adults with RKOA. Overweight/obese and pain are frequently reported as factors associated with inactivity26,27
and as barriers to participating in MV physical activity.25
In fact, pain is the most common barrier to physical activity among adults with arthritis.28
Our sample was consistent with literature that finds that African Americans with osteoarthritis are heavier than Whites and report substantially higher levels of knee pain.24
These findings are relevant to potential public health action targeting overweight/obesity and knee pain in the African American community to reduce future racial/ethnic differences in Guideline attainment.
Importantly, racial/ethnic differences in meeting Guidelines remained substantial, and significant in adults with RKOA after controlling for all assessed socio-demographic and health factors. These persistent differences support the need for future exploration of racial/ethnic barriers to activity. In recent systematic reviews, unsafe neighborhoods, lack of facilities, lack of childcare, and inflexible work environments were the most commonly reported barriers to physical activity among African Americans. 38,39
Common facilitators of physical activity among African Americans included social support, availability of structured/group exercise programs, positive health benefits, a sense of well-being, and weight loss.38
Siddiqi et al concluded that “African American adults clearly stress the need for targeted programs (e.g., through faith-based interventions) and the availability of safe and accessible facilities and places that are conducive to physical activity.” The Centers for Disease Control and Prevention (CDC) recommend six structured, group exercise programs as safe and effective (reduce pain, increase function, improve mood and quality-of-life and delay disability) for adults with arthritis.40
These programs have been delivered in churches, local community centers, etc. in both urban and rural environments and worksites.
Churches can significantly contribute to the health and well-being of African Americans because of their role in communication, social and spiritual support, and the ability to provide safe local facilities.41
Among a sample of African American churches in South Carolina, 42% offered physical activity programs. Church members who reported having physical activity programs at their church were significantly more likely to meet physical activity recommendations.42
Offering evidence-based, low-cost, structured programs in churches may overcome barriers to physical activity reported by African Americans. In addition, a tested CDC community-wide health communication campaign targeted to African Americans and Whites that promotes physical activity for managing arthritis symptoms"Physical Activity. The Arthritis Pain Reliever
”, increased knowledge of the benefits of physical activity for arthritis.43
Health communication campaigns paired with availability of structured community-based physical activity programs may positively increase physical activity participation in African American communities.
Lower levels of physical activity among African Americans compared with Whites, particularly among adults with osteoarthritis who are at high risk for multiple poor health outcomes, is a significant public health issue. African Americans are more likely than Whites to develop obesity and physical inactivity-related chronic conditions such as type 2 diabetes, stroke, cardiovascular disease, and hypertension.44–47
Not only does physical activity improve arthritis symptoms, it lowers the risk of developing these serious conditions.7,8,37
Racial/ethnic disparities in potentially life-threatening conditions may be reduced through culturally targeted programs that promote physical activity and reduce barriers to activity, most notably obesity and knee pain.
This study had substantial strengths, which include the large sample size, objective accelerometer physical activity assessment, radiographic verification of knee OA, the application of current DHHS Physical Activity Guidelines, and the age and gender diversity of this cohort. Accelerometers capture all activity, including occupational, household, and transportation, which may not be well-captured using self-report instruments. However, there are limitations worth noting. Accelerometers lack information on context of physical activity (e.g., transportation, leisure), which may inform culturally relevant activities for interventions. The accelerometer used cannot capture water activities and may underestimate activities with minimal vertical acceleration/deceleration, such as cycling. However, diary information indicated that the median time this sample spent in water and cycling activities was 0 minutes/day (interquartile range = 0.0 to 3.4 minutes/day), so the underestimate is negligible. In addition, OAI is not a population representative sample. Therefore our results here cannot be generalized to the US population.
Despite benefits from physical activity, attainment of 2008 DHHS Physical Activity Guidelines was low for all groups. African Americans were even less likely than Whites to meet Guidelines; this relationship held among persons with or at risk for RKOA. After controlling for differences in socio-demographics and health factors, substantial racial/ethnic differences remained. These disparities were partially mediated by differences in knee pain severity and obesity status. Focused efforts in African Americans to address knee pain severity and weight status may improve physical activity participation and lead to better health outcomes.